Groups of workers on a third-locks project for the Panama Canal returned Thursday to their posts after the European-led consortium in charge of the expansion ended a 15-day shutdown.

Panama's TVN network showed footage of workers arriving at the offices of the GUPC consortium, led by Spain's Sacyr and Italy's Impregilo.

"They called me (Wednesday night) to come to work. We'll see what happens. Maybe they'll fire us," one unidentified worker said.

Another worker said of the presumed resumption of work after a deal announced Wednesday night between GUPC and the Panama Canal Authority, or ACP, that it was the "right decision."

"We're waiting for payment of all worker salaries," Hector Hurtado, a construction workers' union leader who expressed satisfaction at the news.

The ACP said Wednesday night that the consortium had agreed to resume work Thursday, although it added that some issues remained unresolved and were preventing the two sides from putting a definitive end to a dispute that dates back to Dec. 30.

The parties will try to reach agreement on those matters over the next 72 hours, the canal authority said.

Those points include the dates for the delivery of the new lock gates, the timetable for completing the remaining work, the repayment schedule for cash advances the ACP has made to the consortium and "other key aspects for the project's development," the authority said.

The ACP said Wednesday night that "as soon as the work is resumed" it would pay GUPC $36.8 million corresponding to December invoices so that workers receive their wages and the consortium can meet its obligations to its suppliers.

GUPC was awarded the third-locks project - the centerpiece of a $5.25 billion canal expansion - in 2009 with a bid of $3.1 billion.

But it stopped work on the locks - now roughly 70 percent complete - on Feb. 5, saying the project was plagued by some $1.6 billion in cost overruns and demanding that the ACP foot the bill.

The ACP says the project must continue while the two sides agree on a plan to fund the remaining work and notes that the contract provides for independent arbitration of disputes that GUCP and the canal authority can't resolve through negotiations.

The Panama Canal, which was designed in 1904 for ships with a 267-meter (875-foot) length and 28-meter (92-foot) beam, is too small to handle modern ships that are three times as big, making a third set of locks essential. EFE